[PATCH 05/33] sched/isolation: Save boot defined domain flags

Frederic Weisbecker
2025-12-24T13:46:15Z

HK_TYPE_DOMAIN will soon integrate not only boot defined isolcpus= CPUs
but also cpuset isolated partitions.

Housekeeping still needs a way to record what was initially passed
to isolcpus= in order to keep these CPUs isolated after a cpuset
isolated partition is modified or destroyed while containing some of
them.

Create a new HK_TYPE_DOMAIN_BOOT to keep track of those.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
---
include/linux/sched/isolation.h | 4 ++++
kernel/sched/isolation.c | 5 +++--
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index d8501f4709b5..109a2149e21a 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,8 +7,12 @@
#include <linux/tick.h>

enum hk_type {
+ /* Revert of boot-time isolcpus= argument */
+ HK_TYPE_DOMAIN_BOOT,
HK_TYPE_DOMAIN,
+ /* Revert of boot-time isolcpus=managed_irq argument */
HK_TYPE_MANAGED_IRQ,
+ /* Revert of boot-time nohz_full= or isolcpus=nohz arguments */
HK_TYPE_KERNEL_NOISE,
HK_TYPE_MAX,

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 3ad0d6df6a0a..11a623fa6320 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -11,6 +11,7 @@
#include "sched.h"

enum hk_flags {
+ HK_FLAG_DOMAIN_BOOT = BIT(HK_TYPE_DOMAIN_BOOT),
HK_FLAG_DOMAIN = BIT(HK_TYPE_DOMAIN),
HK_FLAG_MANAGED_IRQ = BIT(HK_TYPE_MANAGED_IRQ),
HK_FLAG_KERNEL_NOISE = BIT(HK_TYPE_KERNEL_NOISE),
@@ -239,7 +240,7 @@ static int __init housekeeping_isolcpus_setup(char *str)

if (!strncmp(str, "domain,", 7)) {
str += 7;
- flags |= HK_FLAG_DOMAIN;
+ flags |= HK_FLAG_DOMAIN | HK_FLAG_DOMAIN_BOOT;
continue;
}

@@ -269,7 +270,7 @@ static int __init housekeeping_isolcpus_setup(char *str)

/* Default behaviour for isolcpus without flags */
if (!flags)
- flags |= HK_FLAG_DOMAIN;
+ flags |= HK_FLAG_DOMAIN | HK_FLAG_DOMAIN_BOOT;

return housekeeping_setup(str, flags);
}
--
2.51.1